The Class 43 locos were first constructed from 1975 onwards at Crewe Works. At the time the design was revolutionary, and it would go on to become the most iconic of British Rail locomotives. Their sleek design would become world famous, and when introduced they were known as the High Speed Train, or HST, due to their top speed of 125mph. 197 power cars were built, with the last into traffic in 1982.

When built they were all fitted with the distinctive Paxman Valenta engine, but they have all been replaced with either Paxman VP185 or MTU engines. They have operated over all the former British Rail regions, although they were scarce on the Southern. Currently, it is mainly operated by Great Western, East Midlands Trains, Virgin Trains East Coast, Grand Central and Cross Country Trains. The Great Western and East Coast trains already have their replacements on order, and it remains to see how long they will remain in service.

Only three power cars have been scrapped following high profile accidents,a testament to how well the design would stand the test of time.